Radar signals returned from a target allow information to be determined concerning the slant range, azimuth and speed of a target relative to the receiving system of the radar system. The receiving system however normally receives a number of signals returned from the target which have different propagation paths or modes. Noise received by and induced in the receiving system can also be mistaken for a return signal from the target and needs to be taken into account. Tracking methods have been employed which track a target on the basis of signals relating to one propagation mode. Yet selecting one propagation mode neglects information relating to other modes which can be used to enhance the accuracy and sensitivity of the tracking method.